In Spain, the country's second biggest bank, BBVA, said its earnings slumped due to a drastic rise in provisions, ordered by the government to cover its exposure to the beleaguered real-estate market.

And in Austria, the number one lender Erste Bank, a specialist in Eastern Europe, saw its second-quarter net profit tumble 46 percent owing to problems in Hungary and Romania.

Banks earn a big chunk of their profits from their dealings on financial markets where they have not only sustained losses from falling asset prices, but are also feeling the pain from a downturn in investor activity, said Deutsche Bank's new co-chief executives Anshu Jain and Juergen Fitschen.

"The European sovereign debt crisis continues to weigh on investor confidence and client activity across the bank," the two said.

Deutsche's performance in the April-June period "was impacted by a volatile environment" and net profit fell to 661 million euros ($811 million) in the three months to June from 1.2 billion euros a year earlier. Revenues were down 6.0 percent at 8.0 billion euros.

The drop in profits is fuelling concern whether Deutsche Bank can meet the EU's more stringent capital requirements without issuing new shares to raise additional funds.

But the group insisted that its core Tier 1 capital ratio -- a key measure of financial health -- stood at 10.2 percent at the end of the second quarter, up from 10 percent three months earlier and above the 9.0-percent minimum required by regulators.

Jain and Fitschen were later scheduled to reveal their strategy for steering the banking giant safely through the financial storms, with observers predicting the measures would include job cuts, notably in investment banking.

In Zurich, UBS chief executive Sergio Ermotti said his group was determined to "consolidate its position as the best capitalised bank," topping the 9.0 percent Core Tier 1 capital ratio requirement by the end of this year.

Banking regulators have tightened capital ratio requirements in an effort to prevent any repeat of the risky practices which contributed to the 2008 global financial crisis.

Ermotti was cautious on the outlook for UBS, noting the eurozone debt crisis, US debt levels and geopolitical tensions which will "continue to influence client confidence ... and third quarter activity."

In Spain, BBVA's net profit slumped 57.5 percent to 505 million euros in the three months to June, much worse than analysts' already pessimistic forecasts.

Madrid has ordered Spanish banks to clean up their balance sheets once and for all to ease market pressure that has also driven up the government's cost of borrowing to a level near where other eurozone countries were forced to seek international aid.

The total amount of new provisions expected to be taken by Spanish banks has been estimated at more than 80 billion euros and BBVA said it had set aside 1.43 billion euros in provisions, about a third of the 4.64 billion euros which the bank needs to meet the government's new regulations.

The Spanish government, faced with preventing a potential string of bank insolvencies, has requested an up to 100-billion-euro rescue for its financial sector from eurozone partners.

In Austria, Erste Bank said it had to take a provision of some 200 million euros on its Romanian business after losses at the unit soared to 140.5 million euros from 2.3 million euros in the second quarter 2011.

For the first half of the year, Erste Bank said net profit fell 13 percent from a year earlier to 453.6 million euros but would have been 350 million euros if exceptional financial gains were excluded.